1. Technical Field
The present invention relates generally to an improved structure of a terminal apparatus for electrical connections to a coin-shaped battery which may be employed in portable electronic equipment.
2. Background of the Related Art
FIGS. 12 and 13 show a conventional terminal apparatus for electrical connections to a coin-shaped battery which generally includes a positive terminal plate 22 and a negative terminal plate 25 both made of plate springs. The positive terminal plate 22 consists of a contact portion 23 and a connecting portion 24. The contact portion 23 supported to be engageble with a peripheral side surface of a coin-shaped battery 21. The connecting portion 24 is welded or soldered to a printed-circuit board (not shown). The negative terminal plate 25 consists of a pair of contacts contacting with the bottom of the battery 21 and a connecting portion 27 welded or soldered to the printed-circuit board. The battery 21, is inserted in the direction of arrow 28 as can be seen from FIG. 13, and has a positive electrode 29 and a negative electrode 30. The positive electrode 29 ranges from the upper surface to the side surface of the battery 21, while the negative electrode 30 is formed only on the bottom. In the prior art device per FIG. 13, there may also be included an insulating element 31 which insulates positive terminal 29 from the negative terminal 30. The battery 21, when placed on the terminal apparatus, by insertion in the direction indicated by arrow "28" engages the pair of contacts 26 at the bottom (i.e., the negative electrode 30) and the contact portion 23 at the side surface (i.e., the positive electrode 29).
It is preferable that the contact portion 23 be oriented so as to extend perpendicular to the negative terminal plate 25 for secure engagement with the positive electrode 29 of the battery 21. The contact portion 23 may, however, be inclined, as shown by broken lines A and B in FIG. 13, relative to the negative terminal plate 25 because of locational error during assembling, for example. If the contact portion 23 is inclined outward, as shown by the broken line A, the side surface of the battery 21 is lifted up along a side wall of the contact portion 23, thereby causing the bottom (i.e., the negative electrode 30) of the battery 21 to fail to make contact with the contacts 26 of the negative terminal plate. Alternatively, if the contact portion 23 is inclined inward, as shown by the broken line B, the side surface of the battery 21 is urged downward, thereby resulting in a short circuit between a lower corner of the side surface (i.e., the positive electrode 29) of the battery 21 and the negative terminal plate 25 or the printed-circuit board. This leads to a malfunction of an electronic circuit. If the height C of the contact portion 23 is increased for avoiding such a drawback, it may further cause the contact portion 23 to be deformed elastically or permanently.